Turbochargers are commonly employed for providing improved operating characteristics and improved operating efficiency in internal combustion engines. Turbochargers typically include at least a compressor housing in which a compressor impeller is rotatably disposed and a turbine housing in which a turbine impeller is rotatably disposed, and a shaft linking the compressor impeller and the turbine to insure common operation. The turbine housing is typically connected to the exhaust manifold for receiving exhaust gases from the internal combustion engine so that the exhaust gases will impart energy to rotate the turbine in passing through the turbocharger. When the turbine is rotated, the compressor impeller is likewise rotated, causing compression of the air received into the compressor housing of the turbocharger which is then directed into the intake manifold of the internal combustion engine at a relatively higher pressure. Under ideal conditions, the turbocharger would reach a steady state condition in which the turbocharger would reach an ideal operating speed based on the desired amount of compression to be imparted to the intake air is perfectly balanced with the energy received from the exhaust gases.
In practice, of course, ideal operating conditions cannot be attained. Internal combustion engines are employed in various types of equipment which are operated at different altitudes with respect to sea level, under varying load conditions, and at various throttled engine speeds. When the engine is operated at lower engine speeds, less exhaust gas is available for providing energy to the turbine, as compared to that available at full engine speed. Likewise, as engine speed varies momentarily due to imposed load fluctuations, the amount of available exhaust gas to operate the turbocharger varies. In order to compensate for these changes and fluctuations in operating conditions, it is common to provide bypass valves or "waste gates" to provide a means of controlling the amount of exhaust gases directed from the exhaust manifold into the turbocharger turbine. Numerous examples of prior art may be discovered which provide various control apparatus and methodology for controlling the bypass valve to effectively control the amount of boost or increase in intake air pressure provided by the compressor impeller of the turbocharger.
It is also well known that internal combustion engines operate with the greatest fuel efficiency and the most desirable operating characteristics when the engine has reached its optimum operating temperature. In addition, it is well known that the typical internal combustion engine typically has greater undesirable emissions of unburned fuel when the engine is operating below its optimum operating temperature. In order to bring the typical internal combustion engine up to its desired operating temperature, it has been typical to provide restricted coolant flow, to prevent operation of the radiator fan so as to reduce cooling of the engine coolant, or to employ other similar strategies of controlling the engine coolant system.
The present invention is directed to overcoming one or more of the problems as set forth above.